1. Field of the Invention
The present invention relates to an electronic camera that internally processes image data obtained by picking up subject images. More particularly, the present invention relates to an electronic camera that produces image data for record to be recorded on a recording medium and quickview images for monitor display.
2. Description of the Related Art
In conventional electronic cameras, the following procedures are performed to process image data.    1) Image Capture
An electronic camera reads image data from its internal image sensor. The electronic camera implements signal processings on the image data, such as A/D conversion, defective pixel correction, optical black-level correction, gain adjustment, white balance adjustment, tone correction and so on. The signal-processed image data are stored in a buffer memory within the electronic camera.    2) Image Processing
The electronic camera implements image processings on the signal-processed image data, such as color interpolation, color coordinate transformation, color correction, special frequency filtering and so on, and thereby produce image data for record.    3) Production of Quickview
The electronic camera reduces the image size of the image data for record to produce a quickview image.    4) Production and Compression of Thumbnail
The electronic camera reduces the image size of the image data for record to generate a thumbnail image for a display list. The electronic camera compresses the thumbnail image by use of a hardware or software processing.    5) Image Compression
The electronic camera image-compresses the image data for record by use of a hardware processing or the like.    6) Recording
The electronic camera implements file recording of the image-compressed resultants on a recording medium.
The inventor of the present invention recognizes the following problems existent in the above-described processings.    (1) First Problem
In general, a user or operator of the electronic camera displays a quickview image on its monitor screen after capturing a subject image. He or she may use this quickview image on the photo-taking spot to determine whether the captured result is good or not. It is preferable that the user or operator can check the quickview without delay at the time of photographing. It is, therefore, desirable that the quickview image be produced as soon as possible after the capturing of the subject image.
In the foregoing example of the prior art, however, the image size of the image data for record has to be reduced for generation of the quickview image. In such a case, quick generation of the quickview image is difficult because there is a need for waiting for a completion of generation of the image data for record.
For the generation of image data for record, in general, it is necessary to process full-sized image data. Additionally, in order to improve the picture quality of the electronic camera, those image processings have to be high-level, complicated processings. This tends to elongate the time taken for the processings on the image data for record, and the generation of the quickview image delays accordingly.
For the reason above, the above-described example of the prior art is disadvantageous in terms of availability that a time lag is likely to occur from photographing to displaying the quickview image, so that the user cannot check the captured image smoothly.    (2) Second Problem
Reusing the quickview image during image reproduction can shorten the time required for the image reproduction on the monitor. To prepare for such reuse during image reproduction, it is necessary, when the image data for record is recorded, to record the quickview image together with the image data for record.
In the above-described example of the prior art, the electronic camera must additionally compress and recode the quickview image after completing the image compression of preceding image data for record. This elongates the time required for photographing by a time needed for performing the additional processings accordingly. Consequently, disadvantages such as a reduction in the speed of a continuous shooting are likely to arise.